Can sciatica cause nausea?

Not generally: Sciatica is due to irritation of the sciatic nerve (lumbo-sacral/low back), causes pain in back with radiation to buttocks, legs, typically below the knee. Would not expect it to cause nausea. Of course, some conditions that might cause nausea could give rise to low back pain.

I do not think so: Sometime if you have pain from any source that could make nauseated, but sciatica symptoms does not include nausea.

Possible: Some people who have a lot of pain, can have a vasovagal response in which the body is trying to cope with the pain and can cause you to feel sick to your stomach, dizziness or feeling of passing out.